nukesec1

I have always been a Chevy guy since I bought my first one back in high school. '78 Z28. So I am extemely retarded when it comes to the Olds engine. But I heard somebody say the other day that the Olds BB heads will fit on an Olds SB. Is this true? Or is this guy I heard this from a bigger idiot than me?

gearheads78

Bolt on yes but you will kill the compression because of the larger chambers.

svnt442

And it would require the use of either an Edelbrock Performer RPM or Victor intake due to the taller BBO intake ports.

nukesec1

OK, so the valves are bigger in the BB heads vs the SB from what I have read. As far as the "compression" goes......If I had a SB Olds and put BB heads on it I would have to up the piston compression "alot" to compensate or even see a notable performance increase. Therefore I would really gain nothing by going to a BB head? I told you I was retarded about the Olds power plant. It's kinda like learning to tie my shoes again after 40 years.

nukesec1

That too! I wondered how it would change the geometry of the intake.

nukesec1

Look at the CS in my profile pic. It's granny's car! On one hand I want soooooooo badly to preserve it's 32K mile originality. I want to so, so badly! But, DAMN! I started out thinking "You know, I could put some SSII's with some thin white walls on it because that "was" and option. And that dual exhaust was an option. And so was bullet sport mirrors, it was an option." Now, I'm looking into performance and how I can change or alter this Olds without ruining it's collector value with bolt on stuff. Someone has to stop me from making a grave mistake or sell me a '73 Cut Sup that I can molest!

joe_padavano

Lets clarify a little. All 1964-1990 Olds heads are geometrically interchangeable. The only fundamental external difference between the big block Olds and small block Olds motors is the deck height. It's more like the difference between a Chrysler 383 and 440. All other meaningful geometry (bore centers, port spacing, physical size) is the same.

Yes, there are a number of important internal differences. The big ones as far as head swaps are the head bolt sizes and the chamber size. All 1977-1990 Olds motors use 1/2" head bolts, the 64-76 motors use 7/16" head bolts. Early heads can be drilled to accept later bolts. All BBO motors use 80-ish cc chambers - CR was varied with piston dish size. SBO motors used a combination of dish and chamber size to vary CR. SBO chambers could vary from 60 ccs to about 80 ccs. A lot of folks have successfully installed BBO heads on SBO motors by swapping the pistons to achieve the desired CR.

As noted, the ports and valves are larger on the BBO heads. You can successfully install BBO-sized valve in SBO heads - the factory did it on the W-31 motors. BBO ports are larger than SBO ports, but the "geometry" doesn't change. The only issue is using an intake manifold that has enough meat to be port-matched to the heads.

Nilsson

Do whatever you want with it short of cutting on it. Save the original parts and stash them away for when and if you want to return it to original.

stevengerard

yeah, enjoy it and save the parts, I'd start out with changing rims and leave that for a bit and enjoy it

Eightupman

The engine is 1 1/2" wider at the intake and the centerline (from crank to intake) height is 1/2" (or maybe 3/4") taller

A cast stock 403 manifold is just that beast. It has enough meat to raise the roof and match the port of the BBO head.

Friend of mine is running a set of "E" heads on a 403. Essentially the same combustion chamber as the 4A heads he took off, but without the smaller ports. Of course this is a well build 11-12 second motor.

John

joe_padavano

Since the cylinders are angled at 45 deg, the 1 1/2" wider intake is 3/4" per side, which is the same 3/4" in height. Of course, all of that stems from the approx 1" greater deck height. Geometry is your friend.

Eightupman

Understood. I wasn't disagreeing. I was explaining it differently for those who may not understand "deck height"

I like geometery. I use it in raquetteball.

John